Collapsible container



O United States Patent [1113,540,397

[72] Inventor Robert B. Burns 2,383,840 8/1945 Berckert 222/395X Huntington, New York 2,487,786 11/1949 Bogle 114/05 [211 App]. No. 788,855 2,970,452 2/1961 Beckman et al. 222/3865 [22] Wed 1969 Primary Exanziner Robert B. Reeves [45] i 1970 Assistant Examiner-Norman L. Stack. Jr. [73] Asslgnee Texaco Development Corporation Attorney- K. E. Kavanagh and Thomas H. Whaley New York, New York a corporation of Delaware [54] ABSTRACT: The invention relates to a lightweight liquid holding tank adapted to convey a liquid from a subsea storage [52] US. Cl. 114/05; facility to the water's Surface The tank includes a comronably 222/395 buoyant hull from which an upright canopy support depends. [51] Int. Cl. 1363b 35/00 A ll ible canopy is peripherally fastened to the hull and to [50] Field of Search ZZZ/386.5, the support respectively A Conan Opel-ably carried on the 107, 95, 395; 141/ inquired: l l4/0.5T, 0.5 220/ 13 support, engages the canopy whereby to permit displacement [56] References Cmd of the latter between advanced and retarded positions along the support. The canopy when expanded defines a liquid hold- UNITED STATES PATENTS ing compartment, and when contracted, is collapsed by exter- 1,201,051 10/ 1916 Jack 1 14/05 nal pressure into contact with the hull.

0/71 erc/ ItQ/erZe/e/ A/ma [lire COLLAPSIBLE CONTAINER BACKGROUND OF THE INVENTION Exploration for, and the development of future sources of crude oil have gravitated more toward offshore sites. For example, many offshore areas including portions of the Gulf of Mexico and the Santa Barbara region in California, have proven to be abundant in crude and usable gas. When the over cover of water does not exceed three or four hundred feet, these sources can be tapped, and wells produced by resort to equipment and technology presently available.

However, it has become more apparent that future sources of supply will have to be sought and drawn from deeper offshore sites. As the depth of water increases, and as the distance from shore likewise increases, the problems inherent to an exploring and producing operation escalate commensurably. Such problems are not confined merely to means for obtaining crude oil from the earth, but to the subsequent means for conveying the crude product to a refining facility.

It should be noted that the terminology offshore", as presently and herein used, refers to tideland areas such as an ocean or bay as well as a land locked body of water.

Under ideal circumstances, the withdrawn crude product is piped directly from well head to refinery. Where, however no piping facility is available, resort must be had to tankers, barges or similar means for transferring the liquid. In either instance, the relative cost of operating, and the potential of the oil well or field, are both factors for consideration in determining the most feasible means of transporting the oil.

Among the most practical means for providing a relatively constant flow of oil to a land based refinery or storage area, is by accumulating a predetermined amount of crude oil at a central gathering point communicated with several offshore wells or fields. From this central point, the oil is readily carried to the refinery by the above mentioned tankers or pipeline. In the instance of an oil field with uncertain potential, the feasibility of laying a permanent underwater pipeline is not justified. However, the use of tankers, barges or similar vessels for transferring the crude to the shore refinery is likewise not always financially justified.

One solution peculiar to a relatively provisional facility, is to store the crude liquid in a subsea unit, then periodically remove quantities by way of a transferable tank adapted to carry liquids from the underground storage to the waters surface. The primary drawback to such an arrangement is that the water depth at which the oil is stored, requires the transfer tank to be heavily constructed to withstand the underwater pressure. Thus the construction of such a device will normally include relatively heavy walls together with necessary internal bracing to permit the unit to withstand the subsea pressures.

It is therefore one of the objects of the invention to provide a relatively lightweight liquid holding tank adapted for deep water use. A further object is to provide a liquid holding tank adapted to transverse extreme water depths without being subject to the pressures normally present at such depths. A still further object is to provide a lightweight tank including a yieldable structure adapted to collapse when under external pressure, and to be outwardly expandable thereby to define a liquid holding chamber. Still another object is to provide a lightweight, liquid holding tank adapted to be floatably supported on the waters surface, and thereafter to be lowered to an oil well storage facility whereby said tank might be filled with stored oil or transferred to the waters surface.

In overcoming the herein stated problem with respect to oil and liquid storage, and in achieving the enumerated objectives, there is presently provided a lightweight liquid holding transfer tank adapted for safe convenient submergence to great water depths. The lightweight tank includes a saucerlike flotation hull that will sustain the tank when in unfilled or par tially filled condition, at the waters surface. A fluid-tight flexible canopy sealably connected to the hull outer edge is slidably carried on a support column depending from the hull whereby to define a collapsible liquid storage compartment.

The tank is submergible at an offshore oil storage site to conveniently engage an underwater storage reservoir.

During descent of the tank, external water pressure urges the canopy inward into abutting engagement with the hull surface thereby eliminating the liquid storage compartment. Subsequent pressurized filling of the compartment urges crude oil into the latter as to expand the canopy outwardly. Upon being filled or partially filled, the transfer tank is separable from the reservoir and may be raised to the water's surface to be barged or airborne to a shore based facility.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an environmental view of the present collapsible tank communicated with a subsea, liquid holding reservoir.

FIG. 2 is an enlarged view in partial cross section of the present liquid transfer tank with the flexible canopy shown in the collapsed position.

FIG. 3 is similar to FIG. 2 showing the flexible canopy in the expanded position defining the liquid holding compartment.

Referring to FIG. 1, an offshore installation of the type presently contemplated is illustrated and includes an underwater field consisting of one or more crude oil producing wells. The well heads are at or near the ocean floor and dispersed about a limited area, each being communicated by a pipe or conduit 11 to a main reservoir or storage means 12. The latter comprises a storage vessel formed of steel, concrete, or other material adapted to use in the underwater environment. Vessel 12 is anchored to the ocean floor by piles 13 passing through a skirt or foundation member 14, and imbedded into the ocean substratum.

Vessel 12 may itself be fully, or at least partially imbedded into the floor as a protective measure, however anchoring by piling is normally found to be sufficient.

Crude liquid product received from the dispersed wells is normally under considerable gas pressure and is delivered to the central storage areaat vessel 12 through a manifold system of the necessarypipes, valves and regulators needed to assure a smooth flow. Vessel 12 may as shown, be in the form of a rigid walled container adapted to hold crude oil only. As a matter of practicality however the vessel is usually provided with means to transfer water to and from the storage compartment to maintain the latter in a constantly full condition as the quantity of held oil is varied.

While not presently shown, the underwater facility may be provided with means for separating crude oil into gaseous and other liquid components. In this instance, the degasified crude product would be stored, and the removed gaseous element conducted to the surface either for burning or otherwise disposed of.

Vessel 12 is equipped with the usual liquid flow control means which are automatically or remotely operable. This feature is particularly desirable at water depths exceeding safe diver access depth. Vessel 12 further includes an internal pumping system comprising a pump 16. The latter embodies a suction inlet 17 communicated with a float level mechanism 18, which functions to maintain nozzle 19 in the oil pool whether or not the tank holds water as well as the crude oil.

Pump 16, normally supported on the floor of the reservoir, includes a discharge 9 communicated with an elongated conduit 21 extending upwardly to and through the vessel's roof' 22. A circular collar or fastener 23 sealably positions conduit 21 uprightly with nozzle 24 extending externally of the wall 22. Elongated nozzle 24 is supportably positioned to communicably engage the mating receptacle 28 of transfer tank 26 for automatically providing a flow of crude oil to the transfer tank when the latter is locked onto vessel 12.

A cradle 27 or docking facility supported above vessel 12 includes a rigid guide member. The latter is outwardly flared at the remote upper end to define a seating guide surface for the underside of transfer tank 26 when the latter is being locked into place. At such time, nozzle 24 is sealably received in tank receptacle 28 to form a leak tight annular seal thereby permitting the flow of liquid from vessel 12 to the tank 26 storage compartment whereby the pump pressure causes out ward expansion ofthe tank collapsed canopy 36.

Referring to P16. 2 tank 26 includes a rigid base or hull 31. The latter is considered a hull since it incorporates controlled buoyancy chambers which, when evacuated, will floatably support the transfer tank. Further, flooding of the buoyancy chambers will cause the tank to submerge for connection to the vessel 12.

Hull 31 includes an outer base plate 32. An inner wall 33 is spaced from said plate to define an interwall liquid holding compartment. A series of baffles welded between said base plate and inner wall rigidize and reinforce the base as well as compartmentalize the hull.

As shown in FIGS. 2 and 3, baffles 34, 36 and 37 are generally circular in configuration, being concentrically disposed with respect to the hull to form a series of concentric compartments. Radially disposed panels such as 38 and 39 are terminally connected to the circular baffles whereby to form discrete, circularly arranged segmented chambers.

Each of said segmented chambers is water tight and communicated with a manifold system to regulate the water content of the compartment and consequently the balance and buoyancy of hull 31. While not shown in detail, the manifold system includes necessary piping, valves and regulators, being interconnected with one or more pumps such as pump 16, to controllably regulate the fluid content of the respective buoyancy compartments.

Hull 31 is generally saucerlike in configuration, having one or more hubs 41 upstanding from the inner surface thereof. In the present arrangement, the center positioned hub 41 is adapted to receive and anchor the lower end of canopy sup port 42 within a cavity adapted to tightly engage the support column.

Base plate 32 of the hull includes means to facilitate engagement of transfer tank 26 with the storage vessel 12 prior to, and during transfer of crude oil from the vessel 12 to tank 26. Base plate 32 thus incorporates receptacle 28 in the underside thereof. The receptacle is formed with an inwardly tapered frustoconical wall which leads to a sealing ring 43 at the receptacles constructed end. Ring 43 is adapted to slidably accom modate and lock around nozzle 24 thereby to form a fluidtight annular seal and provide communication between tank 26 and vessel 12. Ring 43 further incorporates a controllable check valve means permitting unidirectional flow of liquid from the tanks liquid storage compartment during such time as the flexible canopy 46 is being inwardly urged thus expelling liquid from the storage compartment during descent into deep water.

The inner wall 32 of hull 31 is peripherally terminated at a rim 44. The external surface of hub 41, rim 44, and the intermediate connecting area therebetween comprises a relatively smooth continuous surface against which collapsible canopy 46 may be urged without risk of damage to the latter. Peripheral rim 44 as shown includes a frustoconical seat 47 against which canopy 46 is compressed to form a fluid-tight annular joint about the hull. Seat 47 may be serrated or otherwise contoured to provide a firm gripping surface against the canopy edge when compressed by sealing ring 48 which includes a lower lip 49 and a clamping face 51.

Ring 48, although extending completely about the tank, is preferably segmented and adapted to be inwardly urged by fastening means 52 such as bolts, clamps, or the like spaced about ring 48 and fastened into seat 47.

Referring to FIGS. 2 and 3, center canopy support column 42 is rigidly held in hub 41 in a generally upright position. The column upper end includes a ring or a similar connection 56 for engaging a lifting mechanism whereby the tank is raised from the water. The latter permits tank 26 to be hoisted to the deck of a vessel, or even lifted by helicopter for transporting a full tank from a well site to a shore position.

Column 42 is cylindrical, having a curved deflecting wall 57 at the lower end disposed across fuel flow passage 58. Wall 57 is preferably formed with a concave surface to deflect a liquid flow from nozzle 24, into radial ports 59. One or more such ports are disposed about hub 41 to communicate with holding compartment beneath canopy 46.

Collar 61 is operably carried on column 42, being slidable from a lower, retracted position as shown in FIG. 2, to an advanced position as shown in HO. 3. Collar 61 includes a spoollike elongated body 62 having an axial bore in which at least one and preferably a plurality of annular seal rings such as 63 and 64 are positioned. Collar 61 further includes a removable cap 66 which fastens to the body upper end whereby to fixedly clamp the center of canopy 46 to the collar, forming a fluidtight seal therebetween, The body outer surface issmoothly contoured to permit the flexible canopy when in a collapsed condition, to lay against the body surface when so urged by external water pressure.

When collar 61 is withdrawn to lower or retracted position as shown in FIG. 2, tank 62 will be in a substantially empty condition. Thus, when tank 26 is submerged beneath the water, external water pressure will urge the canopy inwardly against the inner wall 33 of hull 31. Under such external pressure, air or other fluids held in the tank storage compartment is compressed through a venting valve or port, which valve incorporates a uniflow arrangement. Sealing connection 43 carried in receptacle 58 may thus be provided with a check valve facility to permit evacuation of the fluid holding compartment during descent of the tank 26 and yet, permit filling of the compartment by way of nozzle 24 when the tank has reached and been coupled to the vessel 12.

Canopy 46 which when in the expanded position, defines the liquid holding chamber, comprises material embodying both physical flexibility and chemical resistance to deterioration when in contact with crude oil and/or sea water. Although canopy 46 will not be subjected to excessive physical strain, it may nonetheless be fabricated of a reinforced rubber composition such as metallic mesh imbedded into a rubber coated, body forming material.

As presently shown, canopy 46 is peripherally clamped to the rim 44 of hull 31. A center opening in the circular canopy registers on collar 61 to be sealably clamped thereto.

Operationally, the disclosed liquid transfer tank is adapted for convenient manipulation while at the waters surface and yet is readily engaged to the underwater liquid holding vessel 12. Thus, the transfer tank is relatively light in weight, further, due to the collapsible nature thereof is readily adapted to being conveyed to an offshore site by barge or helicopter. However, the controllably buoyant hull permits the unit to be floated into place at the well site prior to being submerged for connection to the liquid holding vessel.

At the offshore well site, the tank 26 is submerged by at least partially filling the buoyancy control tanks within the hull 31. The tank is then controllably submerged through the water either by guidance from a support means connected to hull 56, or by underwater manipulation.

At the underwater position, the tank is guided and locked into place by cradle 27 fixed to the upper side of vessel 12. The inwardly flared guide surface of hull 31 permits the tank to be properly positioned as to align nozzle 24 with the receptacle 28 of the tank hull 31. As nozzle 24 enters the chamber 58 the nozzle becomes sealably connected at a peripheral joint to the tank by coupling 43 whereby to form a fluidtight passage between the reservoir 12 and the tank storage compartment.

As in the instance of many deep water installations, the pumping system of vessel 12 is automatically or remotely regulated. Thus, with the sealable connection made, a pressurized flow of crude oil held in vessel 12 is pumped through conduit 21 and nozzle 24 into and through radial passages 59. The pressure under which crude oil leaves pump 16 must be in excess of the external pressure acting on the flexible canopy 46, whereby the latter as the liquid flow continues, will be urged outwardly. Thus, with the continued filling of the tank storage compartment, further outward displacement of canopy 46 will cause the collar 61 to be upwardly moved to its advanced condition until abutting the upper end of column 42.

During the filling operation, the buoyancy of the tank 26 might be regulated through a remote connection whereby to either maintain the tank in submerged condition or lighten the same by evacuating the hull. At such time as the tank is in condition to be raised to the waters surface, the hull is controllably evacuated thereby lessening the load on the lifting means, which action will raise the tank to the waters surface.

Such lifting means may comprise a submarine vehicle adapted to engage the tank 26 while in the water, or may include one or more guidelines extending from a barge at the waters surface downwardly for removable connection to the tank 26.

With the tank raised to the waters surface, it might be lifted onto a barge for transporting to shore based refinery or in the alternative, floated to the shore point due to the buoyancy of the hull 31.-

Other modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and only such limitations should be imposed as are indicated in the appended claims.

Iclaim:

1. Lightweight transfer tank for deep water offshore operations, being adapted to convey a liquid cargo from a submerged liquid holding reservoir to the water's surface, which tank includes:

a. a base, including a floatable hull having an inner surface with a peripheral rim;

b. at least one support column having an end fastened at said base and extending normally upward therefrom;

c. a collapsible canopy including an outer edge sealably fixed at said base peripheral rim, and having a central portion;

d. a collar operably received on said at least one column to be longitudinally slidable therealong between advanced and retracted positions; and

whereby, when said collar is urged into the advanced position at said column upper end, the collapsible canopy will be expanded to define with said base inner surface, a fluid holding chamber; and when said collar is at the retracted position, said canopy will be collapsed into engagement with said base inner surface.

2. In a liquid transfer tank as defined in claim 1 wherein; said floatable hull includes means forming a coupling receptacle adapted to sealably engage a filling nozzle communicated with said submerged reservoir of liquid to be transferred.

3. In a lightweight liquid transfer tank as defined in claim 1 wherein; said floatable hull includes; means forming a coupling receptacle in the hull underside, said coupling receptacle including an outer conical guide passage adapted to receive a filling nozzle, and a sealing member in said receptacle adapted to engage a corresponding portion of said filling nozzle to define an annular seal tight joint therewith.

4. In a lightweight liquid transfer tank as defined in claim 1 wherein; said hull includes a flotation system having at least one buoyancy compartment, and pumping means communicated with said at least one compartment for regulating buoyancy of said transfer tank.

5. In a lightweight liquid transfer tank as defined in claim 1 wherein said hullincludes a flotation system having a plurality of discrete buoyancy compartments, said compartments being mutually manifolded to a pumping means, said flotation system being operable to controllably regulate the quantity of fluid in said respective compartments whereby to controllably adjust the buoyancy of said transfer tank.

6. In a lightweight liquid transfer tank as defined in claim 1 wherein; said floatable hull includes an outer base plate, an inner wall spaced from said base plate, a plurality of substantially concentricbaffles disposed internally of said base late and wall respectively and being sealably connected there o to form concentric buoyant chambers therebetween, and a flotation system communicated with said respective discrete chambers including pumping means for controllably regulating the buoyancy ofsaid transfer tank.

7. In a lightweight liquid transfer tank as defined in claim 6 including; radial panels disposed intermediate the respective base plate and inner wall, being fixed thereto to define a plurality of circularly arranged segmented chambers.

8. In a lightweight liquid transfer tank as defined in claim 6 wherein; said pumping means is communicated with the surrounding ocean to transfer water to and from said buoyancy compartments to controllably regulate the buoyancy of said tank.

9. In a lightweight liquid transfer tank as defined in claim 1 wherein; said at least one column is centrally located in said floatable hull,

10. In a lightweight liquid transfer tank as defined in claim 1 wherein; said column includes carrying means at the upper end thereof adapted for engaging a lifting mechanism to raise said tank.

11. In a lightweight liquid transfer tank as defined in claim I wherein said collar includes a clamping lip engaging said collapsible canopy, a central passage adapted to register on said column, and means in said passage for slidably engaging the column outer surface thereby to form a substantially fluid tight seal during movement of the collar.

12. In a lightweight liquid transfer tank as defined in claim 1 wherein said collar includes; a plurality of longitudinally spaced seal rings carried in said central passage and slidably engaging said column outer surface to define a sealing annulus.

13. In a lightweight liquid transfer tank as defined in claim 1 wherein; said collapsible canopy is formed ofa flexible material.

14 In a lightweight liquid transfer tank as defined in claim I wherein said collapsible canopy includes a nonmetallic flexible material having a reinforcing component incorporated therewith. 

